Here is an article about the 10 hottest opera singers. It's a guy so he only refers to girls. And he cheats because he includes Katherine Jenkins twice. However, I must say his selection criteria appear to be much the same as mine: you appear if I can find a nice sexy picture of you. He found two sexy pictures of Katherine Jenkins so....
His list is:
Now I'm not sure all of these admittedly hot women are actually opera singers. For one thing there are a few more microphones in evidence than opera would allow. Rule number one: if you cannot sing in a big hall over a full orchestra without a microphone, you are not an opera singer. It doesn't mean they are not perfectly good singers--they just are not opera singers.
The only three I can be sure of are Anna Netrebko, Elina Garanča and Kate Aldrich.
And maybe this woman:
Have a look.